Material to be printed by an ink-jet printer

ABSTRACT

A printing material  10  wherein a white layer  2  and an absorption layer  3  are formed in this order on a base material  1  made of a resin film. The base material  1  has been made black and opaque, while the white layer contains titanium oxide so as to make it white and opaque. The absorption layer  3  contains a protein and absorbs aqueous inks. Because of containing a hydrophilic and water-resistant binder resin, the white layer  2  is highly compatible with aqueous inks which have permeated the absorption layer  3  and reached the white layer  2 , thereby giving a vivid image.  
     An advertising poster to be adhered to a windowpane of a bus, etc. can be obtained by forming a number of holes  26  in this printing material  10  and then forming an image with the use of an ink jet printer.

TECHNICAL FIELD

[0001] This invention relates to the technical field of printingmaterials. More particularly, it relates to a printing material suitablefor ink jet printers.

BACKGROUND ART

[0002] Advertising posters have been adhered to windowpanes of buses andtrains, windows in buildings, etc. It has been a practice to producethese advertising posters by multi-color printing. Thus, printingmaterials exclusively for multi-color printing are printed by using inkjet printers to give vivid color images.

[0003] When such an advertising poster is adhered to, for example, awindowpane of a bus, it is needless to say that the printed face shouldbe seen from the outside. Moreover, it is favorable that the postercannot be seen in the bus because of its shielding effect but the suncan be shining in through it and passengers can look out of the windowowing to its light transmission properties.

[0004] In FIGS. 4(a) and (b), the numerical symbol 100 stands for anadvertising poster of the above-described type wherein an image 107 isformed on a printing material 110.

[0005] In this printing material 110, a synthetic paper 102 is adheredto a base material 101 made of a black resin film and a number of holes106 piercing through the resin film 101 and the synthetic paper 102 areformed.

[0006] After forming the holes 106 in the printing material 110, anaqueous ink is sprayed onto the synthetic paper 102 with an ink jetprinter. When the aqueous ink 105 permeating the synthetic paper 102 isfixed, a desired image 107 is formed.

[0007] In a case of using this advertising poster 100, it is adhered toa windowpane from the inside with the synthetic paper 102 having theimage formed thereon facing to the window. Thus, the image 107 facesoutside so that it can be seen by pedestrians. Although the black basematerial 101 faces inside, passengers can look out of the window throughthe holes 106. In this case, the inside of the bus cannot be seen fromthe outside, since the holes 106 are very small.

[0008] Since a desired advertisement can be economically made by usingthe advertising poster 100, the demand for posters of this type has beenincreasing in recent years. However, an image printed on the syntheticpaper 102 by using an aqueous ink is blurred, which makes the image 107on the advertising poster 100 of the conventional art unclear.

DISCLOSURE OF THE INVENTION

[0009] The present invention, which has been made to overcome theabove-mentioned troubles encountering in the prior art, aims atproviding a printing material on which a vivid image can be printed byusing ink jet printers.

[0010] To achieve this object, the printing material according to thepresent invention consists of a base material made of a resin film, awhite layer formed on the base material, and an absorption layer formedon the white layer. The above-mentioned white layer contains titaniumoxide and a hydrophilic resin, while the above-mentioned absorptionlayer contains a water-absorbing resin. Moreover, the base material, thewhite layer and the absorption layer are provided with a number of holespiercing therethrough.

[0011] The term “hydrophilic resin” means a resin which wets withoutrepelling water (i.e., having no hydrophobic nature) but does not swellwith water. Water-soluble resins and water-insoluble ones both fallwithin the scope of the hydrophilic resin. In the present invention, usecan be made of, for example, a polyvinyl resin as this hydrophilicresin.

[0012] On the other hand, the term “water-absorbing resin” means a resinwhich swells with water but is insoluble in water. Owing to thesecharacteristics, an aqueous ink can permeate the water-absorbing resin.In the present invention, use can be made of protein in thiswater-absorbing resin.

[0013] In the present invention, it is advantageous for forming anadvertising poster that the base material is a black one.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1(a) provides a sectional view of an example of the printingmaterial according to the present invention. FIG. 1(b) provides asectional view schematically showing the printing material onto which anaqueous ink is sprayed by using an ink jet printer. FIG. 1(c) provides asectional view schematically the printing material wherein the aqueousink has permeated the absorption layer.

[0015]FIG. 2 provides a sectional view of a comparative example whereinthe aqueous ink permeates.

[0016]FIG. 3 (a) provides a sectional view of an example of the printingmaterial according to the present invention provided with holes, whileFIG. 3(b) provides a sectional view schematically showing this printingmaterial onto which an aqueous ink is sprayed by using an ink jetprinter. FIG. 3(c) provides a sectional view schematically showing theprinting material wherein the aqueous ink has permeated the absorptionlayer.

[0017]FIG. 4(a) provides a plan view of an advertising poster producedwith the use of an ink jet printer while FIG. 4(b) provides a schematicsectional view of this advertising poster.

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] In FIGS. 1(a) to 1(c), the numerical symbol 10 stands for theprinting material according to the present invention.

[0019] In this printing material 10, a white layer 2 is formed on a basematerial 1 and an absorption layer 3 is formed on the white layer 2, asFIG. 1(a) shows.

[0020] Now, an example of the process for producing this printingmaterial 10 will be described. First, a black resin film (for example,polyethylene terephthalate (PET) film) having a thickness of about 50 μmwas prepared as the base material 1.

[0021] A titanium oxide dispersion (LN643A manufactured by Resinocolor)was prepared and a POVAL-modified vinyl alcohol polymer (MK2175manufactured by Teikoku Kagaku), having both hydrophilic nature andwater resistance, was added as hydrophilic resin to the dispersion.After mixing by stirring, the resultant mixture was applied onto thebase material 1 to give a predetermined thickness and dried. Thus, thehydrophilic resin exerted an effect as a binder resin on the titaniumoxide, thereby giving a white layer 2 of about 10 μm in film thickness.

[0022] Next, protein (a natural protein) having an average particle sizeof 5 μm (WR450 manufactured by Idemitsu Petrochemical) was applied, as awater-absorbing resin, onto the white layer 2 and dried to thereby forman absorption layer 3 (film thickness: about 30 μm). Thus, the printingmaterial 10 of Example 1 according to the present invention wasobtained.

[0023] Although the base material 1 of this printing material 10 has ablack color, the water-absorbing resin (protein) is a white resin andthe titanium oxide powder is a white pigment. When this printingmaterial 10 is observed from the side of absorption layer 3, therefore,it is white and opaque. When it is observed from the side of the basematerial 1, in contrast, it is black and opaque.

[0024] To use the printing material 10 as described above, it is put inan ink jet printer in such a manner that the absorption layer 3 facesthe printing head and then an aqueous ink is sprayed onto the absorptionlayer 3 from the printing head.

[0025] In FIG. 1(b), the numerical symbol 4 schematically stands for theaqueous ink sprayed onto the absorption layer 3. Owing to the high waterabsorptivity of the protein, the aqueous ink 4 immediately permeates theabsorption layer 3. In FIG. 1(c), the numerical symbol 5 stands for theaqueous ink which has permeated the absorption layer 3.

[0026] Since the hydrophilic resin (the POVAL-modified vinyl alcoholpolymer in this case) contained in the white layer 2 has a hydrophilicnature and water resistance, it is highly compatible with the aqueousink reaching the white layer 1. Since the degree of hydrophilicity ofthe hydrophilic resin in the white layer 2 is lower than that of thehydrophilic resin in the absorption layer 3, the aqueous ink 5 havingpermeated the absorption layer 3 is sustained in the vicinity of thesurface of the white layer 2 and fixed therein. In this step, the whitelayer 2 is exposed to the aqueous ink. However, the hydrophilic resin inthe white layer 2 is not dissolved in the aqueous ink 5 owing to itswater resistance. Thus, a vivid printed image can be obtained.

[0027] Table 1 shows the evaluation data of the printing material 10 asdescribed above (Example 1). TABLE 1 Evaluation data Ink- Water Shield-Film absorp- Blur- resis- Color White- ing crack- tivity ring tancedensity ness effect ing Ex. 1 ∘ ∘ ∘ 1.35 ∘ 87.1 ∘ ∘ Ex. 2 ∘ ∘ Δ 1.09 x90.3 ∘ Δ Ex. 3 ∘ ∘ Δ 1.36 ∘ 85.4 ∘ ∘ C. Ex. 1 ∘ ∘ ∘ 1.24 x   80.7 x ∘ xC. Ex. 2 ∘ x ∘ 0.94 x 89.2 ∘ x C. Ex. 3 ∘ x x 1.27 x 95.0 ∘ ∘

[0028] The item “blurring” was evaluated by printing lines at intervalsof 200 μm on the printing material 10 and the blurred outlines wereexamined with the naked eye. A sample showing no blurring was regardedas “◯” while one wherein adjacent lines united together due to blurringwas regarded as “×”.

[0029] The item “color density” means the evaluation of the dullness andgloss of the printed image. The printing material 10 was subjected toblack printing and the reflection density of the printed matter wasmeasured with a Macbeth densitometer. A sample showing a reflectiondensity of 1.3 or above was regarded as “◯” while one showing a reflexdensity less than 1.3 was regarded as “×”.

[0030] The item “water resistance” was evaluated by subjecting theprinting material 10 to full-color printing, cutting the printingmaterial into small pieces, soaking the pieces in water filled in acontainer for 48 hours at room temperature, then taking out the piecesfrom water and observing changes in the printed matter with the nakedeye.

[0031] A sample causing any change neither in the printed matter nor inthe water was regarded as “◯”, one causing a slight change in the watercolor by dissolved printed matter was regarded as “Δ”, and one whereinapart of the absorption layer 3 was released and dissolved from the basematerial 1 into the water is regarded as “×”.

[0032] The item “whiteness” was measured with the use of a colordifference meter (CR221 manufactured by Minolta Camera) after theformation of the white layer 2 on the black base material 1. Since thebase material 1 has a black color, a higher whiteness indicates thebetter shielding effect. In Table 1, a sample showing a whiteness of 85%or above was regarded as “◯” wile one having a whiteness less than 85%was regarded as “×”.

[0033] Regarding the item “shielding effect”, a sample wherein the backface cannot be seen before printing was ranked higher. When the blackbase material 1 was used, however, all samples were evaluated good.

[0034] The item “film cracking” was evaluated by folding the printingmaterial 10 so as to make the absorption layer 3 top surface andexamining with the naked eye the cracking and falling-out of the coatingfilm (the white layer 2 and the absorption layer 3) at the folded point.A sample showing neither cracking nor falling out was regarded as “◯”wile one suffering therefrom was regarded as “×”.

[0035] Although samples showing evaluation results “Δ” are usable inpractice, those having evaluation results “×”, except the item of colordensity, cannot be put into practical use.

[0036] As Table 1 indicates, the printing material 10 of Example 1 asdescribed above shows favorable results in all of the evaluation items.

[0037] The numerical symbol 20 in FIG. 3(a) stands for a printingmaterial wherein a number of holes (diameter: 3 mm) piercing through theabsorption layer 3, the white layer 2 and the base material 1 are formedin the printing material 10 shown in FIG. 1 (a). When the aqueous ink 24is sprayed onto the surface of the absorption layer 3 as shown in FIG.1(b), the ink layer 25 permeating the absorption layer 3 is sustained atthe white layer 2, as shown in FIG. 1(c). Thus, a vivid image can beobtained similar to the case of Example 1.

[0038] Next, a white layer was formed on the base material by using anacrylic resin (JULYMER SP=50T, manufactured by Nippon Junyaku) as asubstitute for the POVAL-modified vinyl alcohol polymer as thehydrophilic resin in the white layer and dispersing a titanium oxidepowder as such in the acrylic resin as a substitute for the titaniumoxide dispersion. Subsequently, the same absorption layer as that ofExample 1 was formed thereon to give a printing material.

[0039] In this case, the same materials as Example 1, except the whitelayer, were employed and the production conditions were also identicalwith those employed in Example 1.

[0040] Then the thus obtained printing material was evaluated as inExample 1. The results are given in Table 1 (Example 2).

[0041] Since the hydrophilic resin employed in the white layer wasdifferent, the printing material of Example 2 suffered from some filmcracking. Moreover, it was somewhat inferior in the color density andwater resistance to the product of Example 1, though no trouble wascaused thereby in practical utilization.

[0042] Next, a white layer was formed on the base material by using annondenaturation polyvinyl alcohol polymer (PVA 235, manufactured byKuraray) as a substitute for the POVAL-modified vinyl alcohol polymeremployed in Example 1 as the hydrophilic resin in the white layer.Subsequently, the same absorption layer as that of Example 1 was formedthereon to give a printing material. In this case, the same materials asExample 1, except the hydrophilic resin in the white layer, wereemployed and the production conditions were also identical with thoseemployed in Example 1.

[0043] Then the thus obtained printing material was evaluated as inExample 1. The results are given in Table 1 (Example 3). Since thehydrophilic resin employed in the white layer was an nondenaturationone, the printing material of Example 3 was somewhat inferior in thewater resistance to the product of Example 1, though no trouble wascaused thereby in practical utilization.

[0044] Next, a printing material 50 was formed, as a comparativeexample, by forming an absorption layer 52 directly on the base material51, as shown in FIG. 2. Then the thus obtained printing material wasevaluated as in Example 1.

[0045] The data of Comparative Example 1 given in Table 1 indicate theresults of the evaluation of this printing material wherein the samematerials as those in Example 1 were used as the base material 51 andthe absorption layer 52.

[0046] In Comparative Example 2 given in Table 1, the same material asin Example 1 was used as the base material 51. However, the absorptionlayer 52 was formed by dispersing a titanium oxide powder and adding theprotein and polyester resin and a hardly yellowing polyurethane resin tothe same protein as used in Example 1.

[0047] In Comparative Example 3, a printing material 110 was formed byadhering a synthetic paper 102 to a base material 101, as shown in FIG.4 (b).

[0048] As Table 1 shows, the sample of Comparative Example 1, which hadno layer containing white pigment (titanium oxide), was inferior inwhiteness due to the yellowing caused by protein. Since the whitepigment (titanium oxide) used in Comparative Example 2 had nohydrophilic nature, the aqueous ink permeated the water-absorbing resin52 nonuniformly, thereby resulting in a low color density.

[0049] Although the above description is made on printing materialshaving a water-absorbing resin exposed on the surface, printingmaterials wherein a transparent resin film is laminated on the surfaceof the water-absorbing resin after printing also fall within the scopeof the present invention.

INDUSTRIAL APPLICABILITY

[0050] As described above, the printing material according to thepresent invention is suitable for ink jet printing and a vivid image canbe obtained thereby with the use of aqueous inks. Thus, multi-colorprinted advertising posters with high qualities can be obtained therebyeconomically.

Scope of claims:
 1. A printing material which consists of: a base material made of a resin film; a white layer formed on said base material; and an absorption layer formed on said white layer; characterized in that: said white layer contains titanium oxide and a hydrophilic resin; said absorption layer contains a water-absorbing resin; and a number of holes piercing through said base material, said white layer and said absorption layer are formed therein.
 2. The printing material as claimed in claim 1, characterized in that said hydrophilic resin has water resistance.
 3. The printing material as claimed in claim 2, characterized in that said hydrophilic resin is a polyvinyl synthetic resin.
 4. The printing material as claimed in claim 3, characterized in that said water-absorbing resin contains protein.
 5. The printing material as claimed in claim 4, characterized in that said base material has a black color. 